Managing Stress with Dysthymia: Seeking Advice

I was recently diagnosed as of last year with PDD, but nobody has really told me how do I manage stress. I feel like I try to acknowledge it, to let it go with meditation. But, that fails and I just end up holding it in until I emotionally spiral into hopelessness and failure. And I feel like crying for hours while wondering if I matter at all. So my question is what do you guys do to destress while living with Dysthymia?